There are no published data regarding compliance with anti-tuberculosis preventive therapy among children in Australia and limited published data worldwide. This study aimed to determine the compliance rate among 6-year-old children prescribed preventive therapy for tuberculosis infection. A prospective cohort study was conducted on 78, 6-year-old children prescribed antituberculosis preventive therapy. Compliance was measured by compliance with prescribed preventive therapy as reported by parents who were administered questionnaires on completion of the course. In a subsample of 44 children, the proportion of children who complied with scheduled visits to the hospital, and pharmacy records of isoniazid dispensed were used as measures of compliance. Questionnaire data indicated a reported compliance rate for completion of the 6-month course of preventive therapy of 70.5% (55 children). For those 55 who reported completing the full course, 91% reported missing less than 1 tablet per week. In the subsample of 44 children, only 59% attended all follow-up clinic visits, and 54% collected all 6 months of isoniazid prescribed. Compliance with antituberculosis preventive therapy is suboptimal. Improved methods to measure compliance and strategies to optimise compliance with preventive therapy is required.